Re: control of 83 link port

To: CALC-TI@LISTS.PPP.TI.COM
Subject: Re: control of 83 link port
From: Grant Stockly <gussie@ALASKA.NET>
Date: Fri, 7 Nov 1997 19:17:36 -0700
Reply-To: Grant Stockly <gussie@ALASKA.NET>

Here are the key items most people need for using the 83 link port.  I've
taken out all the trash and here is the cream filling.

Also, this is what people most get confused with.  (Near the bottom)

Grant Stockly

The TI-83 link port uses 2 data lines, D0 & D1, for communicating.

THE DATA LINES ARE READ IN AS HIGH (1) WHEN NO ACTIVITY IS PRESENT ON THE
DATA LINES.
sample reading the data lines :
        IN      A,(BPORT)       ; READ THE VALUE OF THE B-PORT
        CP      0Ch             ; ANY DATA LINE GO LOW ?
        JR      Z,NO_ACTIVITY   ; IF READ 0Ch THEN NO LINES LOW

        CP      8               ; IS D0 PULLED LOW ?
        JR      Z,D0_LOW        ; YES, BIT 2 = 0 SO D0 IS LOW NOW

sample writing to the data lines :
        LD      A,D0LD1L
        OUT     (BPORT),A    ; is used for setting D0 low, D1 low

        LD      A,D0LD1H
        OUT     (BPORT),A    ; is used for setting D0 low, D1 high

        LD      A,D0HD1L
        OUT     (BPORT),A    ; is used for setting D0 high, D1 low

        LD      A,D0HD1H
        OUT     (BPORT),A    ; is used for setting D0 high, D1 high


BPORT and data line commands and hex values:

        D0LD1L      EQU              0C3h       : D0 low D1 low
        D0LD1H      EQU              0C1h       ; D0 low D1 high
        D0HD1L      EQU              0C2h       ; D0 high D1 low
        D0HD1H      EQU              0C0h       ; D0 high D1 high
        BPORT       EQU              0          ; BPORT

Prev: Sound on the TI-86
Next: Introducing the TI-92 Plus Module
Index(es):
- Main
- Thread